Over the last two decades, I must have acquired at least a couple of thousand Euros worth of electronics test equipment. Collecting test equipment, most like-minded individuals would consider understandable, after all, who doesn't like tinkering. But measuring equipment without components to measure stuff off of, is of no use to a tinkerer, so add to that a few thousand more Euros worth of components to the bill of acquired goodies - while knowing all the while that 99% of them I will never use! But, as the saying goes, "possession is nine-tenths of the law", and I'd rather possess, when the possession is needed - never mind that most of the unused possessions will eventually end up in a skip at some time in the future.
Case in point, is the Mastech Bench PSU. This was bought 10-15 years ago as a replacement, after I had smoked a beloved, though less-capable supply, with high voltage, and that I had 'liberated' from an employer in the distant past. The Mastech performed well for years. After a while, I would notice that the displayed voltage would fluctuate a bit, but no biggie. Over a year or two, that observance became an irritant, then quickly became an annoyance. I remember at the time, trawling through Reddit, searching for a solution. On the plus side, I learned that the Mastech - one of a handful of names that it was known as - all in all, was seen by most, as fairly reliable. Jittery voltage displays was noted however, along with the consensus that either reservoir electrolytics or the voltage pots, needed replacing.
In my head, I poopoo'ed the potentiometer solution, mainly because on my PSU, both supplies fluctuated badly, despite, by my reckoning, the right-hand side having been the main work-horse, the left having had sparse usage. So caps it was, I decided, and promptly ordered some. But, as an afterthought, I added a bag of assorted pots to the BOM, just in case...
And there both lay, gathering dust, for the best part of two years - enough time, that I had even forgotten about having ordered the pots! By this time, the voltage fluctuations had gotten so bad, that I had grown fearful of damaging circuits I was powering it with. A capacitor-swap was the first thing I tried, and that proved to have zero effect. I was chuffed to discover, on rummaging around my boxes of components, the bag of pots I had ordered. Long story short, the potentiometers proved to have been the culprits! Once replaced, both supplies returned to being fluctuation-free - RESULT!
Wee!
